Maybe it's a regional thing. I've never heard it described in any meetings as a required practice, but everyone in the Dallas and North Texas chapter seems to do it, so I do as well when I'm the R. They seem to like blowing the whistle to indicate their presence when they enter the floor as well - I still don't do that.

Now this is a common practice around here. Several other Texans on here have said the same for their area.

I haven't found the need to do it yet but I'm not working a whole lot of games with above the rim action at this point.

Different twist
 

Suppose in the OP, the visiting bookkeeper was sitting with the home scorer and V12 comes to table to report. Official book says "I got no V12" and visiting keeper says "Oh, you must have left him off, his name is Bird, Larry" Home book just adds Larry and in he goes. They tell the officials LATER. It's now "discovered", but it's already "occurred".

I would be very, very happy. Play on.

Play on and explain to the home coach that it was his scorer who made the addition without telling us in the proper time frame.

Or tell him that the name was in the visiting scorebook and his scorer failed to copy it down.

An eraser?

I can't think of a better time to trot out 2-3.

Either way, there's no T.

If it's not penalized when the name is added, it's too late to penalize.

There's a case or interp on this.

TEAM TECHNICALS
10.1.2 SITUATION: (a) Three minutes prior to the start of the game; or (b) during a time-out in the second quarter of play, the Team B coach requests the scorer to add a name to the team list or change a team member's number in the scorebook. When is the penalty invoked for this administrative infraction? RULING: The infraction occurs when the scorer is advised to add to or change the scorebook. The foul must be charged when it occurs and enforced when the ball next becomes live. Once the ball has become live, it is too late to penalize.

I Hate It When This Happens ...
 

Many administrative infractions can involve the scorebook and rosters. If a team adds a name to the team roster after the ten minute time limit, then a team technical foul is charged. When such a player legally enters the court, the player’s name and uniform number must be entered into the official scorebook. In order to penalize this infraction, the offending team member must be one of the five players currently in the game. In addition, if a team requires the official scorer to change a team member or player’s uniform number in the official scorebook (with exception), after the ten minute time limit, then a team technical foul is charged. If there is no request for change, or if a team member does not become a player, thus avoiding the change, there is no penalty.

Similarly, if a team requires a player to change to a number in the official scorebook after the ten minute time limit, then a team technical foul is charged. A maximum of one team technical foul is charged regardless of the number of players, and substitutes, not wearing the number indicated in the official scorebook. Each player must wear the number indicated in the official scorebook, or change the official scorebook number to that which the player is wearing. Any additional substitutes who become players and require the changing of the number indicated for them in the official scorebook will not result in a penalty, as the one maximum technical has already been charged to the team for this administrative infraction. If there is no request for change, or if the team member does not become a player, thus avoiding the change, there is no penalty.

Three scorebook situations: adding a name to the team roster, changing a name or a number in the official scorebook, and/or having a player change a uniform number, are penalized with a team technical foul when they occur, after the ten minute time limit. These infractions occur when the scorer is advised to add to or change the official scorebook. The foul must be charged when it occurs and enforced when the ball next becomes live. Once the ball becomes live, after such changes have been made to the scorebook, it is too late to penalize. Remember, the ball becomes live when: on a jump ball, the tossed ball leaves the referee’s hand; on a throw-in, it is at the disposal of the thrower; and on a free throw, it is at the disposal of the free thrower.

After the ten minute time limit a team is charged with a maximum of one technical foul regardless of how many infractions of the following are committed: changing a designated starter, adding a name to the team member list, requiring the scorer to change a team member’s or player’s number in the scorebook, requiring a player to change to the number in the scorebook, and/or having identical numbers on team members and/or players. Each player must wear the number indicated in the scorebook, or change the official scorebook number to that the player is wearing. Any additional substitutes who become players and require the changing of the number indicated for them in the official scorebook will not result in a penalty, as the one maximum technical has already been charged to the team for that team’s administrative infraction

Why can you NOT change a foul or uncall a T? We do it on out of bounds all the time. Last year I called a charge because I was straight lined and didnt see the defender push the offensive player into the other defender. My partner just didnt blow a whistle but after I made the call told me what happened. Seemed only right to change from charge to push.

Also couple years ago a head coach had a heart attack in a college game and the officials didnt know what was going on and charged the coach with a T. The NCAA suspended them and said they should have rescinded the T. We can do whatever we please as long as its within the rules and it makes sense.

Here rescinding the T makes perfect sense.

There is a difference between conferring with your partner after a preliminary signal and going back to a foul that was assessed prior to the last live ball. You can only go back to fix correctable errors and this isn't a correctable error.

Rescinding the T would not be within the rules.

Just My Opinion ...
 

Coach requests, and is granted a timeout. Official home scorekeeper states that it is his sixth time out. Official charges team with a technical foul. Before shots are taken, the official home scorekeeper, and the visiting scorekeeper, confer and decide that an error was made in the offcial home scorebook, and that the coach did not use a timeout in excess of the limit.

Call me a fool, but I'm taking back the charged techincal foul.

Sure they should have rescinded it; before the FTs were taken. Your case is the same thing, you changed your call prior to the ball being made live (FT or throwin). Same thing with OOB calls.

Let's use the OOB call here.
You call blue.
Just after blue inbounds, your partner realizes you missed something he saw so he blows his whistle and comes to you saying blue had tipped it last.

Assuming he's right; too bad.

Same thing with your foul scenario; once you shoot the first free throw, it's too late. Even if your partner tells you there was a push or a travel that happened first.
There has to be some cutoff, and the pervasive precedent seems to be once the ball is live, it's too late. The exception seems to be with throwins, once it's completed it's too late. Even then, that would indicate you could correct/rescind the T up until the point where the first free throw is completed (at the absolute latest).